# how can i get new positions of rotated rectangular?

ok... lets forget about my creative(?) drawing and wrting first.

I have an rectangular image. There are four of image points which re sizes the image when user drags it.

$4$ points : $(0, 104)$, $(93, 104)$, $(0, 0)$, $(93, 0)$

It seems each point working fine but problem happens if user rotates the image. As the image is rotated, the points also should be repositioned.But I am not sure how to find changed positions.

If I rotates the image $30$ degrees, how can I get new repositioned value of for positions?

For example $(0, 104)$ $\dashrightarrow$ after 30 degree change $\dashrightarrow$ $( ?, ?)$

I am not really familiar with this kind of problems. Can you guys at least give me a hint or guide me where to start to solve this problem?

Thanks in advance.

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1) I assume the "offset" is the point you're rotating the image around? 2) Are you familiar with rotation matrices? (If not I suggest you google it; wikipedia has a nice entry.) – Gyu Eun Lee Jan 15 '13 at 7:26
yes... you are right offset is the center point I roatating the image around. thanks for the suggest. I am trying to figure out rotation matrices but already had headache :( – Seho Lee Jan 15 '13 at 7:47
this should be helpful – Adam Jan 15 '13 at 7:52
adam/// thanks a lot dude! – Seho Lee Jan 15 '13 at 7:55